The field of the invention is structural members, and the invention relates more particularly to truck body construction.
The side wall of truck bodies is generally formed from plywood with an aluminum or plastic exterior surface. One such construction is shown in applicant's U.S. Pat. No. 4,222,606 which shows a truck body made of plywood panels joined at their vertical intersection by aluminum, panel-joining rails having an inner recess for a caulking compound. An extruded structural system is disclosed in U.S. Pat. No. 4,557,091. U.S. Pat. No. 4,084,272 shows a plastic extrusion used in swimming pools. An overflow gutter system is shown in FIG. 7, but in both of these patents, there is not a sufficient protection against bending between adjacent rails. The constructions shown in these two patents would not be satisfactory for a side wall made of many horizontal rails.
With the ever increasing interest in fuel economy, there is a need for truck body sidewalls of lighter weight. Also, for some applications, such as the transportation of oxygen, it is important to have a nonflammable truck body built from material that will not burn.